Polish-Swedish Wars

The Polish-Swedish Wars occurred from 1600 to 1629 within the context of the Thirty Years' War. The wars saw the Kings of Sweden launch repeated invasions of Poland-Lithuania in an attempt to acquire more territory from the Poles, while the Polish king Sigismund III Vasa unsuccessfully attempted to reclaim the throne of Sweden from his uncle, the usurper King Charles IX of Sweden, and his branch of Sigismund's House of Vasa. Ultimately, the wars resulted in Sweden making minor territorial acquisitions in the Baltics.

History
Sigismund III Vasa, King of Poland-Lithuania from 1587 to 1632, also reigned as King of Sweden from 1592 to 1599. The son of King John III of Sweden, he reigned as king with his uncle Charles serving as regent for him. However, Sigismund's Catholicism alienated the majority of Protestant Sweden, including his Lutheran uncle Charles, who overthrew him after defeating him in battle in 1599. Charles' usurpation of power set the stage for several wars between Sweden and Poland, two of the most powerful states in Eastern Europe at the dawn of the 17th century.

War of 1600-11
In 1600, war broke out between Charles and Sigismund, nominally over control of Estonia and Livonia, but especially due to the dispute over the throne. The Polish szlachta supported the conflict due to its desire to acquire more lands after an easy struggle, but they underestimated Sweden's military power. The Swedes had numerical superiority due to the Poles' concurrent focus on the wars between magnates in Moldavia and the Swedes took control of Estonia and most of Livonia. Polish chancellor Jan Zamoyski, recalled from Moldavia, would reconquer much of the lost territory by 1602, and Hetman Jan Karol Chodkiewicz succeeded Zamoyski as commander after Zamoyski fell ill. He often won against superior odds, but the Polish government faced bankruptcy due to its decentralized financial system. In 1605, the Swedes also faced bankruptcy after raising a new massive army, but the Tsardom of Russia provided the Swedes with financial support in order to distract Poland from intervening in the Time of Troubles. In September 1605, Chodkiewicz won a glorious victory at Kircholm (in what is now Latvia), but his army would go on to plunder the estates of rival lords, reducing his army to a mere collection of mercenaries. In 1611, following the death of King Charles IX, a truce was declared, and it lasted until 1617.

War of 1617-18
In 1617, the young king of Sweden, Gustavus Adolphus, ended Sweden's "Ingrian War" with Russia and, with the support of the fellow Protestant states of England and Holland, set his sights on Livonia. The powerful Swedish navy occupied almost the whole Livonian coast, but the Lithuanians under Field Hetman Krzyzstof Radziwill recaptured almost all of the strongholds except for Parnu, and the Lithuanians annexed the Duchy of Courland and Semigallia into the Grand Duchy of Lithuania. In 1618, a new truce between Poland and Sweden was signed, and it was agreed that Parnu would temporarily remain in Swedish hands.

War of 1621-25
In 1620, Poland-Lithuania went to war with the Ottoman Empire, and Gustavus Adolphus decided to exploit Poland's momentary weakness by invading once more. The Swedes took Riga after a month's siege and three assaults, and the Swedes captured the Courlander capital of Mittau without resistance. In January 1622, the Swedes captured Valmiera and several other Livonian castles, but the Poles under Hetman Radziwill would again reverse the Swedish gains. As the two sides began a prolonged battle at Mittau, both sides signed a truce in 1622, which in 1623 was prolonged until 1625.

King Sigismund hoped that he could reclaim the throne of Sweden from his uncle's line, and he had Spanish Navy officers train a new Polish fleet, which was manned by local Kashubian fishermen and carried English mercenary marine infantry. On 27 June 1625, Gustavus Adolphus landed in Livonia with 20,000 Swedish troops, re-igniting the conflict. The Swedes invaded Livonia and Lithuania, cutting links between the Polish garrisons in Livonia and Lithuania while capturing several major fortresses. In October 1625, Radziwill retook several castles, while his rival hetman, Lew Sapieha, fought off the Swedish assault on Daugavpils. On 17 January 1626, in the Battle of Wallhof, the Swedes won their first victory against the Poles in open battle, and the Swedes stopped three attacks by the hussars at the Battle of Gniew in September-October 1626.

War of 1626-29
Content with the performance of his troops, Gustavus Adolphus decided to take the war to Royal Prussia. In May 1626, he invaded Polish Prussia, and the neutral Duchy of Prussia gave its passive support to the Swedish invaders. However, Gustavus Adolphus failed to capture Gdansk, having been fought to a draw at Gniew. In 1627, Hetman Stanislaw Koniecpolski recaptured the port of Puck from the Swedes, and the Swedes were defeated at the Battle of Czarne while attempting to attack Koniecpolski's army from several sides. In June 1627, Gustavus Adolphus was wounded while crossing the Vistula River at Kiezmark, and he was wounded again at the Battle of Dirschau in August. A Polish fleet defeated a Swedish flotilla at Oliwa in November, but the bankrupt Poles were forced to halt their offensives in 1628, leading to the Swedes returning to the offensive. However, epidemics wiped out large numbers of men and horses in the Swedish garrisons, weakening their occupation forces. In 1629, a corps of troops from the Holy Roman Empire under Fiedl Marshal Hans Georg von Arnim-Boitzenburg was sent to assist the foundering Poles against the Swedes, and another corps under Albrecht von Wallenstein was sent to Pomerania. At the Battle of Trzciana on 25 June 1629, Gustavus Adolphus was almost killed or captured twice while fighting against the Imperial-Polish armies, and the fighting in Prussia devolved into stalemate. In 1629, a ceasefire was declared in favor of the Swedes, to whom Poland ceded the larger part of Livonia together with its important port of Riga. The Swedes also kept the Prussian cities of Pillau, Memel, and Elbing, becoming the dominant power on the southern coast of the Baltic Sea.

Aftermath
King Sigismund and King Gustavus Adolphus both died in 1632; Sigismund in his bed in Warsaw, and Gustavus Adolphus on the battlefield at Lutzen during the Thirty Years' War. The rivalry between Poland and Sweden would continue for decades, especially during The Deluge of 1655-1661 and the Great Northern War of 1700-1721. In 1668, John II Casimir Vasa, the last Vasa ruler of Poland, was forced to abdicate after a short but bloody civil war, and his successor Michal Korybut Wisniowiecki ushered in a series of Polish kings from several different dynasties (Wisniowiecki, Sobieski, Wettin, Leszczynski, and Poniatowski).